From: Avi Kivity <avi@redhat.com>
To: Stefan Hajnoczi <stefanha@gmail.com>
Cc: Stefan Hajnoczi <stefanha@linux.vnet.ibm.com>,
kvm@vger.kernel.org, "Michael S. Tsirkin" <mst@redhat.com>,
qemu-devel@nongnu.org, Christoph Hellwig <hch@infradead.org>,
Khoa Huynh <khoa@us.ibm.com>
Subject: Re: [Qemu-devel] Re: [PATCH 2/3] virtio-pci: Use ioeventfd for virtqueue notify
Date: Wed, 01 Dec 2010 14:30:21 +0200 [thread overview]
Message-ID: <4CF63FDD.7040901@redhat.com> (raw)
In-Reply-To: <AANLkTikw4V0UJyVs9StXCSkcHfKRxNBsaY6eZ4-P2y6d@mail.gmail.com>
On 12/01/2010 01:44 PM, Stefan Hajnoczi wrote:
> >>
> >> And, what about efficiency? As in bits/cycle?
> >
> > We are running benchmarks with this latest patch and will report results.
>
> Full results here (thanks to Khoa Huynh):
>
> http://wiki.qemu.org/Features/VirtioIoeventfd
>
> The host CPU utilization is scaled to 16 CPUs so a 2-3% reduction is
> actually in the 32-48% range for a single CPU.
>
> The guest CPU utilization numbers include an efficiency metric: %vcpu
> per MB/sec. Here we see significant improvements too. Guests that
> previously couldn't get more CPU work done now have regained some
> breathing space.
Thanks for those numbers. The guest improvements were expected, but the
host numbers surprised me. Do you have an explanation as to why total
host load should decrease?
Seems to me the host is doing more work, and doing it less efficiently
(by ping-ponging requests to another thread).
In any case, looks like good improvement with no downsides.
--
error compiling committee.c: too many arguments to function
next prev parent reply other threads:[~2010-12-01 12:30 UTC|newest]
Thread overview: 23+ messages / expand[flat|nested] mbox.gz Atom feed top
2010-11-11 13:47 [Qemu-devel] [PATCH v2 0/3] virtio: Use ioeventfd for virtqueue notify Stefan Hajnoczi
2010-11-11 13:47 ` [Qemu-devel] [PATCH 1/3] virtio-pci: Rename bugs field to flags Stefan Hajnoczi
2010-11-11 13:47 ` [Qemu-devel] [PATCH 2/3] virtio-pci: Use ioeventfd for virtqueue notify Stefan Hajnoczi
2010-11-11 15:53 ` [Qemu-devel] " Michael S. Tsirkin
2010-11-12 9:18 ` Stefan Hajnoczi
2010-11-12 9:25 ` Michael S. Tsirkin
2010-11-12 13:10 ` Stefan Hajnoczi
2010-11-11 16:45 ` Christoph Hellwig
2010-11-12 9:20 ` Stefan Hajnoczi
2010-11-14 10:34 ` Avi Kivity
2010-11-14 10:37 ` Stefan Hajnoczi
2010-11-14 11:05 ` Avi Kivity
2010-11-14 12:19 ` Avi Kivity
2010-11-15 11:20 ` Stefan Hajnoczi
2010-12-01 11:44 ` Stefan Hajnoczi
2010-12-01 12:30 ` Avi Kivity [this message]
2010-12-01 21:34 ` Stefan Hajnoczi
2010-12-06 15:09 ` Avi Kivity
2010-11-11 16:59 ` Avi Kivity
2010-11-11 17:12 ` Michael S. Tsirkin
2010-11-11 17:55 ` Gleb Natapov
2010-11-11 13:47 ` [Qemu-devel] [PATCH 3/3] virtio-pci: Don't use ioeventfd on old kernels Stefan Hajnoczi
2010-11-11 17:46 ` [Qemu-devel] Re: [PATCH v2 0/3] virtio: Use ioeventfd for virtqueue notify Michael S. Tsirkin
Reply instructions:
You may reply publicly to this message via plain-text email
using any one of the following methods:
* Save the following mbox file, import it into your mail client,
and reply-to-all from there: mbox
Avoid top-posting and favor interleaved quoting:
https://en.wikipedia.org/wiki/Posting_style#Interleaved_style
* Reply using the --to, --cc, and --in-reply-to
switches of git-send-email(1):
git send-email \
--in-reply-to=4CF63FDD.7040901@redhat.com \
--to=avi@redhat.com \
--cc=hch@infradead.org \
--cc=khoa@us.ibm.com \
--cc=kvm@vger.kernel.org \
--cc=mst@redhat.com \
--cc=qemu-devel@nongnu.org \
--cc=stefanha@gmail.com \
--cc=stefanha@linux.vnet.ibm.com \
/path/to/YOUR_REPLY
https://kernel.org/pub/software/scm/git/docs/git-send-email.html
* If your mail client supports setting the In-Reply-To header
via mailto: links, try the mailto: link
Be sure your reply has a Subject: header at the top and a blank line
before the message body.
This is a public inbox, see mirroring instructions
for how to clone and mirror all data and code used for this inbox;
as well as URLs for NNTP newsgroup(s).